Key Engineering Materials Vol. 818

Abstract: This study is to examine substances which can protect the polymer composites against gnawing from rodent. Polyvinyl chloride (PVC) compound acted as polymer matrix was mixed with anti-rodent substances in internal mixer. Several substances were added in PVC namely: denatonium benzoate (DB), capsaicum oleroresin (CO), deltamethrin (DM), caffeine, pepper, salt, wasabi and essential oil. There were 6 sets of anti-rodent samples. The percentage of weight loss of each sample was recorded and compared. The result showed the best repellent substances were DB and CO giving bitter taste and burning sensation to the rodent, respectively. The best anti-rodent composites are samples in set 6 consisting of DB at concentration of 1.961 wt% and SiCO at concentration of 12.162 to 23.529 wt%.

Abstract: This research studied the influence of treated water hyacinth fibers with chemical substances and the orientation of water hyacinth (WH) fiber reinforced bio-based epoxy composite on mechanical properties. The specimens with direction at 90˚, 45˚ and 0˚ of WH fiber and different treatment substance were investigated. Sodium hydroxide (NaOH) and (3-Aminopropyl) triethoxysilane were used for the chemical treatment of fiber, which can improve the mechanical properties of the composite. The result shows that the tensile modulus of 1% silane treated WH fiber is higher than neat epoxy around 15%. The orientation of the fiber affects directly on the tensile strength. The addition of the WH fibers improves impact properties in all conditions compared to original epoxy.

Abstract: Cassia fistula gum was purified and modified by isopropanol precipitation and carboxymethylation process respectively. The physicochemical property of both purified and modified gums were evaluated and compared to their crude gum. The mannose to galactose (M/G) ratio of purified gum was altered by purification process. While, the carboxymethyl groups were formed via carboxymethylation for modified gum, indicated by IR spectra. As expected, the physicochemical properties of both purified and modified gums were better than crude gum.

Abstract: The C. fistula gums in aqueous solutions clearly exhibited shear-thinning flow behavior at high shear rate, however, at higher concentrations, pronounced shear thinning was observed. The value of zero shear viscosity [h₀] was predicted by fitting Cross model. A plotting of specific viscosity at zero shear rate (h_sp0) against coil overlap parameter (C[h]) was shown the linear slope of dilute and simi-dilute as 1.43 and 4.10, respectively, which found the critical concentration (C*) about 7.08/[h]. While, the mechanical spectra in the linear viscoelastic region of gum solutions showed the typical shape for macromolecular solutions.

Abstract: Plasma technology is an effective way to modify the physicochemical properties of silk fabric. This study was a preliminary study to explore the dyeability of silk fabric with metal complex dyes after treated with plasma technology, which may improve the processability and broaden the application of silk fabric. This study investigated the optimal plasma treatment condition and evaluated treated silk fabric in terms of wettability, surface modification and dyeability. It was found that plasma treatment can enhance the wettability and dyeability of silk fabric via the formation of hydrophilic functional groups in the structure of silk fiber.

Abstract: Thermal property is an importance factor of quick dry inner wears. This study aims to evaluate the thermal property of women’s quick dry inner wears in the market with different market position (Brand A: online brand; Brand B: general market and Brand C: youth market). The thermal property studied in this paper included (i) thermal conductivity and (ii) Q-max value (warm/cool feeling). The thermal conductivity and Q-max values were measured according to the standard of KES-F7. Thermal conductivity analysis showed that Brand B was the optimal product, while Q-max results indicated that both Brand B and Brand A had the best product in terms of quick dry property.

Abstract: Carbonated Hydroxyapatite (CHAp) is hydroxyapatite (HAp) substituted with carbonate ions that are similar to natural bone inorganic constituents. CHAp based on abalone mussel shells (Halioitis asinina) with calcination temperature variations were successfully synthesized using the precipitation method. Abalone mussel shells powder was calcined at 650, 800 and 1000°C for 4 hours, that aimed to obtain calcium oxide (CaO) which has the best characteristics as a source of calcium (Ca) in the CHAp synthesis process. The effect of calcination temperature variations on the characteristics of abalone mussel shells powder was investigated and characterized using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Energy Dispersive X-Ray Spectroscopy (EDX). In this study, calcination temperature variations affected the crystalline phase and the percentage of calcium (Ca) and carbonate (CO₃^2-) ions. The results of the characterization show that the calcination temperature at 1000°C is the optimum temperature to obtain CaO powder as a source of calcium (Ca) in CHAp synthesis.

Abstract: Incorporation carbonate ion to hydroxyapatite (HAp) structure, known as carbonated hydroxyapatite (CHAp) is reported to reduce crystallinity, increase the solubility rate, and increase bioactivity. Sintered CHAp material is interesting because it may have a better biological response.CHAp derived from common cockle (Cerastoderma edule) shell have produced by precipitation method. This study aimed to investigate the effect of sintering temperature to compositon and crystal characteristics of CHAp. CHAp powder was sintered at 400, 600, and 800°C in air atmosphere.CHApas-preparedand sintered samples were analyzed using Energy Dispersive Spectrometry (EDS), Fourier Transform Infrared (FT-IR), and X-ray Diffractometer (XRD).EDS analysis showed that the Ca/P ratio of powder CHAp was around 1.67-1.94 (greater than the Ca/P ratioof HAp). For increasing of sintering temperature, carbonate and water content decreased, crystallinity and crystallite size increased.

Abstract: Carbonate Hydroxyapatite (CHAp) is one of biomaterial that can be synthesized from natural ingredients. CHAp has been successfully synthesized from pearl shells (Pinctada maxima) using the precipitation method. The pH of the synthesis process affects several characteristics of CHAp, including crystallinity, crystal size, morphology, and carbonate content. XRD data showed that CaO obtained from pearl shell powder through the calcination process. The highest crystallinity of CHAp occurs when the pH is 8, and the lowest is at pH 10. The size of the crystalline CHAp decreased when the pH increased. Based on SEM data, the morphology of CaO looks more tenuous than the morphology of CaCO₃ due to CO₂ release during the decomposition process. The magnitude of pH greatly influences the morphology of CHAp where morphology looks different for different pH. EDX data shows that CHAp has the highest carbonate content when pH 10 with a smaller Ca/P ratio when the carbonate content gets bigger.